Seagate Technology Incorporated

Shawn Alan Wakefield

Brett Alan Sloan

Jimmie Ray Shaver

Robert Matousek

Timothy Ted Walker

Jeffrey A Heydt

Karl Louis Enarson

Daniel Thomas Kiser

An apparatus and method are disclosed for improving data recovery operations in a disc drive employing a redundant sync data block format. The disc drive includes a rotatable disc and a controllably positionable head which is used to store user data in a plurality of data blocks on tracks of the disc. Each data block includes a user data field to store user data, a first sync field and a redundant, second sync field, the sync fields storing first and second sync words, respectively, which establish symbol boundaries used by a read channel of the disc drive. User data are recovered from a selected data block by initiating a delay of selected duration during which a first portion of the selected data block passes proximate the head, allowing the second, remaining portion of the selected data block to be read at the completion of the delay. Data can thus be recovered in the presence of mis-sync errors, wherein a selected sync word is detected early or late by one or more bits, as well as from non-contiguous data blocks that are split into two fragments to accommodate a coincident servo block.

Data recovery in a disc drive with redundant sync data blocks

The present invention uses temperature readings obtained aperiodically, on demand. Rather than merely obtaining temperature readings on each expiration of a fixed timer, operating parameters are updated in response to a fault detected in the data path. Data handling systems of the present invention each include at least one data path having a thermal range within which it operates best. Applicant notes that some &ldquo;key&rdquo; operating parameters typically have a substantial effect on this thermal range. Temperature sensors positioned near the transducers provide a temperature reading to control circuits, which update &ldquo;key&rdquo; operating parameter values in response to indications of faults in a primary data path. This reduces the need for more frequent temperature monitoring and calculation-intensive recalibration.

Thermally compensated data handling system using aperiodic temperature readings

A method and system for providing adaptive threshold levels for detecting thermal asperities where a unique threshold level is determined for each head. In addition, a unique threshold level is also set for each head at various locations on a disc. In particular, a threshold level for a first head in a first track is determined wherein the threshold level is initially set at a minimum threshold level and is subsequently increased by a threshold level increment until a detection is not made. These steps can be repeated for the first head in a second track and a second head in a first and second track. A memory saves the determined threshold levels.

Method and system for detecting thermal asperity on discs used in a disc drive

An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. Attached to one end of the actuator assembly is one or more transducers. The disc includes data areas and servo areas written at angular locations on the disc. The disc drive also has a disc drive controller which includes a motor speed controller, a write gate controller, and a device for predicting the disc speed at an upcoming servo and disabling the write gate if the predicted disc speed is outside a selected range of disc speeds. The device for predicting the disc speed may further include an abort signal generator that produces an inhibit write gate signal in response to the predicted disc speed being outside the selected range of disc speeds.

Motor speed observer for data protection in a disc drive

An apparatus and method are disclosed for optimizing the operational performance of a disc drive having a head adjacent a rotatable disc, a servo circuit which controls the position of the head and a read channel for decoding read signals from the head to reconstruct data previously stored on the disc. The read channel includes a channel quality monitor which generates a channel quality measurement indicative of read channel quality, the channel quality measurement determined from error values associated with the data reconstructed by the read channel from the read signal. An optimum value for a selected parameter affecting disc drive performance is selected by determining an associated quality measurement value for each of a plurality of parameter values, and selecting the optimum value for the parameter in relation to the associated quality measurement values. Preferably, each associated quality measurement value is determined in less than one revolution of the disc.

Parametric optimization using disc drive read channel quality measurements

An apparatus and method are disclosed for optimizing write performance of a disc drive through the use of write thresholds that are adaptive by head and by disc location. The disc drive has a head which is controllably positionable adjacent each of a plurality of nominally concentric tracks defined on a rotatable disc, which selectively magnetizes the tracks to write data to the tracks. A servo circuit of the disc drive controls the position of the head and prevents the head from writing data to the tracks until the head is positioned within write thresholds which are separately defined for each of the tracks. The write thresholds for each of the tracks are stored in memory and accessed by a digital signal processor of the servo circuit at the commencement of each write operation by the disc drive.

Write fault thresholds adaptive by head and disc location in a disc drive

A method is disclosed for optimizing write performance of a disc drive through the selection of optimum write thresholds. The disc drive has a controllably positionable head adjacent tracks defined on a recording surface of a rotatable disc. A narrow head detection test is first applied whereby data are written to a selected track while maintaining the head at a first off-track center distance. The data are read while maintaining the head at a position nominally over the center of the selected track and measuring resulting read error performance. These steps are then repeated using a second off-track center distance. A wide head detection test is next applied, by writing data to the selected track while maintaining the head over the center of the selected track, writing data to an adjacent track abutting the selected track while maintaining the head at a third off-track center distance, and reading the data while maintaining the head over the center of the selected track and measuring resulting read error performance. These steps are then repeated using a fourth off-track center distance. The optimum write thresholds are thereafter selected from the measured read error rates.

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Norman, OK, United States of America

Shawn Alan Wakefield